When you drag out any type of CMS, or product grid, you are essentially given several parent divs that do nothing but hold the div inside them.
While I've wondered why we need so many, it has largely been not a big problem.
What is more confusing though, and a wasted opportunity, is that you can't put anything else in those divs.
The reason I think we should be able to, is because once this is attached to a CMS or product list, that we could use conditional visibility based on the items within the list.
For example, I am working on a template page that has three grids containing products that are sorted both for that page, and for the individual grid. Above each grid is a label denoting what products are in that section. This is working great until one of the sections is empty, then I have a label with nothing under it. If it was nested in the hierarchy of the grid, I could use conditional visibility, but as it is I can't, because the condition it needs is within the grid (which is a sibling element, and not a parent), not the page.
Additionally, it would be tidier to be able to have things in here, as it would make this more of a self contained unit, and would allow layouts to have fewer items.